That's generally the big thing, yes; still the problem(s), but the physical symptoms are pulling back to whatever degree, meaning it's notably easier to actually express the rest of it. Still, it could be something else, too, including just straight up increased aggression and whatnot, or some other side effect that's causing it*. One of the trickier things about antidepressants (That I figure vec is already aware of/the doctor has emphasized, but still) is that people just don't react the same way to any particular one very often -- there's general themes and likelihoods, but it's a great deal of trial and error, often leaning towards the error side of things until something workable is found. It can be pretty rough, both for the person taking them and the people that care for 'em.
Which... yeah. Best of luck, vec, and definitely keep in contact with the doctor, especially if he's been taking them long enough the effects should have kicked it. Hopefully the prescribing doctor told you/your family this, yeah.
*I've actually just recently started on some myself, and one of the physical side effects for the initial dosage was uncontrollable tremors in my basically everything -- if I had even the most remote of tempers, I probably would have been a nightmare to be around when it was particularly bad, because holy fuck you cannot easily maintain composure when you're constantly losing fine (and sometimes not) motor control.